The Pediatric Oncology Program Project at the University of Minnesota is directed toward improving the understanding of pathophysiology of disease and treatment. Surface markers in leukemia and lymphoma patients have received special emphasis. These specific membrane characteristics have proven to be both significant prognostic factors and insightful into cellular origin. Lymphocyte response to mitogen stimulation will provide evidence of unresponsiveness as an indicator of clinical exacerbation and/or immunoincompetence induced by chemotherapy. The bone marrow transplantation (b.m.t.) center is now established. This study will analyze by controlled methodology, the potential superiority of b.m.t. in AML. Fifty (50) patients so treated in 4-5 year courses will be compared to a larger number (100) treated by standard maintenance. The marrow capacity for sustaining colony growth and the ability to form colony stimulating factor will be measured in bone marrow transplantation donors and recipients as well as during graft versus host episodes. Cyclophosphamide metabolism and pharmacokinetics will be scrutinized in order to provide improved rationale for treatment. Analysis of cyclophosphamide metabolites in blood, urine and leukemic cells with and without other chemotherapeutic agents will be analyzed by GLC mass spectrometric deuterium labelled methodology. Monocyte-macrophage system as seen originally in patients will be studied in order to determine the role of this system in original leukemic patients and during subsequent chemotherapy. Platelet reactivity (prostaglandin and nucleotide metabolism) of leukemic patients will be studied in order to understand cellular response to original disease and subsequent treatment.